swuferhong commented on code in PR #3511: URL: https://github.com/apache/fluss/pull/3511#discussion_r3464078584
########## fluss-server/src/main/java/org/apache/fluss/server/metadata/PartitionNegativeCache.java: ########## @@ -0,0 +1,141 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You under the Apache License, Version 2.0 + * (the "License"); you may not use this file except in compliance with + * the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +package org.apache.fluss.server.metadata; + +import org.apache.fluss.annotation.VisibleForTesting; +import org.apache.fluss.utils.clock.Clock; +import org.apache.fluss.utils.clock.SystemClock; + +import javax.annotation.concurrent.ThreadSafe; + +import java.time.Duration; +import java.util.concurrent.ConcurrentHashMap; +import java.util.concurrent.atomic.AtomicLong; + +/** + * A thread-safe negative cache for partition IDs that are known to not exist in ZooKeeper. + * + * <p>This cache helps reduce ZooKeeper pressure when clients repeatedly request metadata for + * partitions that have been deleted (e.g., during hourly partition rotation). Instead of querying + * ZK every time, we cache the "not exist" result and return it directly. + * + * <p>The cache uses access-time-based TTL: entries are evicted after a configurable duration of no + * access. As long as clients keep asking for the same non-existent partition, the cache entry stays + * alive and protects ZK. + */ +@ThreadSafe +public class PartitionNegativeCache { + + /** Default TTL for negative cache entries: 10 minutes of no access. */ + private static final Duration DEFAULT_TTL = Duration.ofMinutes(10); + + /** + * Cleanup interval: only run eviction check when at least this many milliseconds have passed + * since the last cleanup. + */ + private static final long CLEANUP_INTERVAL_MS = 60_000; + + private final ConcurrentHashMap<Long, Long> cache; Review Comment: I have changed it to guava cache -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
